The preparation of bromonitroalcohols is described in U.S. Pat. No. 3,658,921. The disclosed process comprises reacting a nitroalkane with an aldehyde and an inorganic salt of a member of the group consisting of magnesium and alkaline earth metals in an aqueous medium to form the magnesium or alkaline earth metal salt of a nitroalcohol. This nitroalcohol salt is then brominated without isolation in an aqueous suspension at a temperature below 25.degree. C.
More recent U.S. Pat. No. 3,711,561 also describes a process for preparing bromonitroalcohols. The disclosed process comprises reacting a nitroalkane with an aldehyde and an alkali metal hydroxide in the presence of water to obtain an aqueous solution of the alkali metal salt of the nitroalcohol and reacting the aqueous solution with bromine at a temperature less than 25.degree. C.
Both of these patents disclose that procedures involving the isolation of the salts of the nitroalcohols cause great difficulties. These difficulties include the very time consuming filtration and purification of such salts and the high instability of these salts. The patents disclose that attempts have been made to avoid these difficulties by effecting the halogenation step before the added condensation by first halogenating the nitroalkane to form the corresponding halonitroalkane and reacting the halonitroalkane with an aldehyde to form the halonitroalcohol. While this process is said to have been quite good in the case of long chain nitroalkanes, unsatisfactory results are said to have been obtained with short chain nitroalkanes, particularly with nitromethane.